Velocity pumping system

ABSTRACT

In one aspect, the present invention provides a surface unit for a pumping system. The surface unit may include a conduit that is reciprocatable to pump produced fluid from downwell to the surface unit and a flow line in fluid communication with the conduit such that the produced fluid may be collected from the conduit. The surface unit may also include a pump barrel that separates the conduit from a well tubing and a diluent line in fluid communication with a space between the pump barrel and the well tubing. The diluent line may be sealed from the conduit and the flow line such that a diluent or lubricant may be delivered to the space between the pump barrel and the well tubing via the diluent line without contaminating the produced fluid.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part application and claims thebenefit of copending U.S. patent application Ser. No. 14/224,979, filedMar. 25, 2014, the complete disclosure of which is herein incorporatedby reference.

BACKGROUND OF THE INVENTION

Pumping well fluids from wells penetrating producing formations has beendone for many years. Often, heavy viscous oil must be moved to thesurface. This oil can be found relatively close to the earth's surfaceand can contain sand and/or other solid particulate and can be difficultto pump. The presence of sand and other solids in conventional pumps cancause numerous problems, such as premature wear and/or jamming of thepump. The wear and jamming can result in high costs associated withdowntime, repair, replacement, and cleanup. Additionally, the wear cancreate safety concerns, both for the drill crew and for the environment.

Some problems of conventional pumping systems can be attributed to theplunger and its connection to the drive rods. For example, sand can gettrapped between a pump plunger and a pump barrel. As the pumpreciprocates up and down in the pump barrel during operation, the sandrubs against the plunger, other pump components, and the pump barrel,causing the pump to wear excessively.

The connection between the drive rods and the pump in conventionalsystems can contribute to the buildup of the damaging precipitate.Specifically, the connection of the drive rod and plunger components inconventional pump systems is positioned at the top of the plunger. Sandcan stack up on the top of this connection, causing the plunger to stickin the barrel when there is a power failure or power to the pump isotherwise shut off. Additionally, the geometry of the connectorcontributes to the problem. Oftentimes, conventional connectors aretapered outward such that any solids are funneled down and outwardtoward the interface between the inner wall of the pump barrel and theouter diameter of the plunger. This creates more opportunity for sand orother particulate to get between this interface and cause wear to thepump.

Conventional connectors often have a slightly smaller outer diameterthan that of the plunger. For example, connector may have an outerdiameter that is 1/60,000 of an inch smaller than the outer diameter ofplunger. Because of such a configuration, sand tends to accumulatebetween the connector and the pump barrel upon reciprocation of theplunger. On further operation, the accumulated sand, coarse particulate,or other solids will find its way between the pump barrel and theplunger. As such, significant problems may occur with the pump,including stuck plungers, gaulded plungers and barrels, reduced pumpefficiency, and shortened pump life.

Other problems related to sand and other precipitate in the producedfluid may arise due to the overall pump structure. Problems related to agas build up preventing actuation of valves within the pumping systemcan cause the system to lock up. In conventional pumps, a hydrostaticfluid column above the pump holds a single traveling valve closed untila pressure under the traveling valve exceeds the pressure created by thehydrostatic fluid column above the traveling valve. If too much gas getsinside the pump barrel and compresses, then the traveling valve will notopen and the pump is in a gas locked state.

In conventional pump systems, the pumped fluid flows through a maintubing section that is outside of an aperture of the plunger. Solids maysettle out of the pumped fluid and on top of the pump, cementing orotherwise sticking the pump within the tubing. In conventional systems,when stuck, the pump cannot be retrieved by merely pulling the pump outwith the drive rods. Instead the replacement of components of the pumpdownwell requires that the main tubing structure be removed anddisassembled to access the pump, causing the pumped fluid within themain tubing structure to be spilled. This is called pulling a wet well,which can create environmental and safety problems. Improvements inhandling of sand and gas within downwell pumping systems are desired.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the present invention serve to provide systems andmethods to improve the ability of a pump to handle sand and other solidswithin a production fluid. Plungers having tapered pointed tips at theirouter periphery ensure a tight fit within a pump barrel, preventingsolids from getting between the plunger and the pump barrel and causingexcessive wear. In some embodiments, hollow drive rods can serve as aconduit for the production fluid travel to the surface. A series ofcheck valves and/or traveling valves can ensure that the pump system canhandle both solids and the introduction of gas trapped within theproduction fluid.

In one aspect, the present invention provides a surface unit for apumping system. The surface unit may include a conduit that isreciprocatable to pump produced fluid from downwell to the surface unitand a flow line in fluid communication with the conduit such that theproduced fluid may be collected from the conduit. The surface unit mayalso include a pump barrel that separates the conduit from a well tubingand a diluent line in fluid communication with a space between the pumpbarrel and the well tubing. The diluent line may be sealed from theconduit and the flow line such that a diluent or lubricant may bedelivered to the space between the pump barrel and the well tubing viathe diluent line without contaminating the produced fluid.

In another aspect, the present invention provides a pumping system. Thepumping system may include a conduit having a top end and a bottom end,wherein the top end is coupleable with a surface pumping unit and a flowline in fluid communication with the conduit such that the producedfluid may be collected from the conduit. The pumping system may alsoinclude a pump barrel that separates the conduit from a well tubing. Thepump barrel may include a standing valve. The pumping system may alsoinclude a diluent line in fluid communication with a space between thepump barrel and the well tubing. The diluent line may be sealed from theconduit and the flow line such that a diluent or lubricant may bedelivered to the space between the pump barrel and the well tubing viathe diluent line without contaminating the produced fluid.

The pumping system may further include a plunger assembly coupled to theconduit near the bottom end. The conduit may be translatable toreciprocate the plunger assembly within the pump barrel using anupstroke and a downstroke. The plunger assembly may include a plungerreciprocatably positioned within the pump barrel. The plunger may havean inner diameter, an outer diameter, a bottom end, and an open top endwith a tapered edge that is tapered from the inner diameter toward theouter diameter to form a tip aligned with the outer diameter. Theplunger assembly may also include a connector coupled with the bottomend of the conduit and with the plunger at a position below the top end.The connector may be configured to permit fluids to be moved upwardlythrough the connector and the conduit upon each downstroke of theplunger assembly. The top end of the plunger may be adapted to directparticulate into the plunger and away from the pump barrel upon eachupstroke. The plunger assembly may also include a traveling valvepositioned at a bottom end of the plunger. Upon each upstroke, thetraveling valve may be closed and the standing valve may be opened tocause a vacuum within the pump barrel to draw fluid into the plungerassembly below the traveling valve. Upon each downstroke, the travelingvalve may be opened and the standing valve may be closed to force thefluid through the traveling valve and through the conduit to thesurface.

In another aspect, the present invention provides a method for pumpingfluids from the ground. The method may include placing a pumping systeminto the ground. The pumping system may include a conduit having a topend and a bottom end, wherein the top end is coupleable with a surfacepumping unit and a flow line in fluid communication with the conduitsuch that the produced fluid may be collected from the conduit. Thepumping system may also include a pump barrel that separates the conduitfrom a well tubing. The pump barrel may include a standing valve. Thepumping system may also include a diluent line in fluid communicationwith a space between the pump barrel and the well tubing. The diluentline may be sealed from the conduit and the flow line such that adiluent or lubricant may be delivered to the space between the pumpbarrel and the well tubing via the diluent line without contaminatingthe produced fluid.

The pumping system may further include a plunger assembly coupled to theconduit near the bottom end. The conduit may be translatable toreciprocate the plunger assembly within the pump barrel using anupstroke and a downstroke. The plunger assembly may include a plungerreciprocatably positioned within the pump barrel. The plunger mayinclude an inner diameter, an outer diameter, a bottom end, and an opentop end with a tapered edge that is tapered from the inner diametertoward the outer diameter to form a tip aligned with the outer diameter.The plunger assembly may also include a connector coupled with thebottom end of the conduit and with the plunger at a position below thetop end. The connector may be configured to permit fluids to be movedupwardly through the connector and the conduit upon each downstroke ofthe plunger assembly. The top end of the plunger may be adapted todirect particulate into the plunger and away from the pump barrel uponeach upstroke. The plunger assembly may also include a traveling valvepositioned at a bottom end of the plunger. Upon each upstroke, thetraveling valve may be closed and the standing valve may be opened tocause a vacuum within the pump barrel to draw fluid into the plungerassembly below the traveling valve. Upon each downstroke, the travelingvalve may be opened and the standing valve may be closed to force thefluid through the traveling valve and through the conduit to thesurface.

The method may also include reciprocating the conduit and plungerassembly within the pump barrel with at least one upstroke and at leastone downstroke. The method may further include closing the travelingvalve and opening the standing valve upon each upstroke to create avacuum within the pump barrel and plunger assembly to draw fluid intothe plunger assembly below the traveling valve. The method may includeopening the traveling valve and closing the standing valve upon eachdownstroke to force the fluid through the traveling valve and throughthe conduit to the surface and directing particulate into the firstplunger through the open top end and away from the pump barrel upon eachupstroke with the tapered edge.

In one aspect, the present invention provides a plunger for use in apumping system. The plunger can include a cylindrical plunger body thatis adapted to be coupled to a drive rod. The plunger body can define anaperture configured to receive pumped fluids. The aperture can define aninner diameter of the plunger body. The plunger body can include aleading end having a tapered peripheral portion configured to directsolids inwardly into the aperture. The tapered portion can be taperedfrom the inner diameter toward an outer diameter of the plunger body toform a tip aligned with the outer diameter. The tapered portion caninclude two or more different degrees of taper along a length of thetapered portion. The plunger body can further include a rear endcoupleable to a traveling valve.

In some embodiments, the tapered portion can include a first section anda second section. The first section can have a different degree of taperthan the second section. The first section can include a leading edge ofthe plunger. The first section can have a lower degree of taper than thesecond section. In some embodiments, the first section and the secondsection each can have a taper within a range of about 5 to 80 degrees.In some embodiments, the first section can have a taper of between about5 to 30 degrees and the second section can have a taper of between about45 to 75 degrees. In other embodiments, the tapered portion can includean arc having a constant radius. The tapered portion can include an archaving a variable radius. In some embodiments, the leading end of theplunger comprises a pointed tip at the outer periphery. In otherembodiments, at least some surfaces of the plunger can include a wearresistant or lubricating coating.

In another aspect, the present invention provides a pumping system. Thepumping system can include a pump barrel adapted to be placed into awell casing. The pump barrel can include a standing valve. The pumpingsystem can also include a conduit having a top end and a bottom end. Thetop end is coupleable with a surface pumping unit. The conduit can becoupled to a plunger assembly at the bottom end and is translatable toreciprocate the plunger assembly within the pump barrel using anupstroke and a downstroke. The plunger assembly can include a plungerreciprocatably positioned within the pump barrel. The plunger can havean inner diameter, an outer diameter, a bottom end, and an open top endwith a tapered edge that is tapered from the inner diameter toward theouter diameter to form a tip aligned with the outer diameter. Theplunger assembly can also include a connector coupled with the bottomend of the conduit and with the plunger at a position below the top end.The connector can be configured to permit fluids to be moved upwardlythrough the connector and the conduit upon each downstroke of theplunger assembly. The top end of the plunger can be adapted to directparticulate into the plunger and away from the pump barrel upon eachupstroke. The plunger assembly can also include a traveling valvepositioned at a bottom end of the plunger. Upon each upstroke, thetraveling valve is closed and the standing valve is opened to cause avacuum within the pump barrel to draw fluid into the plunger assemblybelow the traveling valve. Upon each downstroke, the traveling valve isopened and the standing valve is closed to force the fluid through thetraveling valve and through the conduit to the surface.

In some embodiments, the plunger is a first plunger and the taperedportion is a first tapered portion, and the pumping system furtherincludes a second plunger reciprocatably positioned within the pumpbarrel and spaced apart and coupled with the first plunger. The secondplunger can include an open bottom end with a second tapered edge thatis tapered towards an inner wall of the pump barrel. The bottom end ofthe second plunger can be adapted to direct particulate into the plungerand away from the pump barrel upon each downstroke.

In some embodiments, the first tapered edge and the second tapered edgeeach include a first portion tapered toward the inner wall of the pumpbarrel and a second portion tapered toward the inner wall of the pumpbarrel. The first portion can have a different degree of taper than thesecond portion. In some embodiments, the first portion can include ataper of between about 5 to 30 degrees and the second portion caninclude a taper of about 45-75 degrees. In other embodiments, the firsttapered edge and the second tapered edge each form a pointed tip. Eachpointed tip can have a diameter at the outer periphery that is within0.001 inches of an inner diameter of the pump barrel. In other words,the tolerance between the tip and the pump barrel is about 0.001 inchesto about 0.002 inches. In some embodiments, the pumping system canfurther include at least two traveling valves disposed between the firstplunger and the second plunger. In other embodiments, the conduitfurther includes a plurality of check valves disposed along a length ofthe conduit. In some embodiments, at least one of an outer diameter ofeach of the first plunger and the second plunger or an inner diameter ofeach of the first plunger and the second plunger includes a lubricatingwear resistant coating.

In another aspect, the present invention provides a method for pumpingfluids from the ground. The method can include placing a pumping systeminto the ground. The pumping system can include a pump barrel adapted tobe placed into a well casing. The pump barrel can include a standingvalve. The pumping system can also include a plunger assembly. Theplunger assembly can include a conduit for transporting pumped fluid.The conduit can be disposed within the pump barrel and can have a topend and a bottom end. The top end can be coupleable with a surfacepumping unit. The plunger assembly can further include a plunger havingan open top end with a tapered edge. The plunger may be reciprocatablypositioned within the pump barrel. The plunger can have an innerdiameter, an outer diameter, a bottom end, and an open top end with atapered edge that is tapered from the inner diameter toward the outerdiameter to form a tip aligned with the outer diameter. The plungerassembly can include a traveling valve disposed at a bottom end of theplunger. The plunger assembly can also include a connector coupled tothe plunger below the open top end and coupled with the bottom end ofthe conduit. The connector is configured to permit fluids to be movedupwardly through the connector and the conduit during operation of theplunger assembly. The method can further include reciprocating theconduit and plunger within the pump barrel with at least one upstrokeand at least one downstroke. The method can include closing thetraveling valve and opening the standing valve upon each upstroke tocreate a vacuum within the pump barrel and plunger assembly to drawfluid into the plunger assembly below the traveling valve. The methodcan further include opening the traveling valve and closing the standingvalve upon each downstroke to force the fluid through the travelingvalve and through the conduit to the surface. The method can alsoinclude directing particulate into the first plunger through the opentop end and away from the pump barrel upon each upstroke with thetapered edge.

In some embodiments, the plunger is a first plunger and the methodfurther includes reciprocating a second plunger having an open bottomend with a tapered edge. The second plunger can be coupled with thefirst plunger. The method can further include directing particulate intothe second plunger through the open bottom end and away from the pumpbarrel upon each downstroke with the tapered edge. In other embodiments,the tapered edge includes a first portion tapered towards an inner wallof the pump barrel and a second portion tapered towards the inner wallof the pump barrel. The first portion can have a different degree oftaper than the second portion.

In another aspect, the present invention provides a plunger assembly.The plunger assembly can include a connector coupleable to areciprocatable rod. The connector can be configured to permit fluids tobe moved upwardly through the connector upon a downstroke of the plungerassembly. The plunger assembly can include a first plunger having aninner diameter, an outer diameter, a bottom end, and an open top endwith a tapered edge that is tapered from the inner diameter toward theouter diameter to form a tip aligned with the outer diameter. Thetapered edge can have two or more different degrees of taper along alength of the tapered edge. The first plunger can be coupled with theconnector at a position below the top end. The first plunger can beconfigured to reciprocate within a pump barrel. The top end of the firstplunger can be adapted to direct particulate into the first plunger andaway from the pump barrel upon an upstroke of the plunger assembly. Theplunger assembly can further include a traveling valve have a top endand a bottom end, the top end of the traveling valve being positioned ata bottom end of the first plunger. The plunger assembly can also includea second plunger comprising an inner diameter, an outer diameter, a topend, and an open bottom end with a tapered edge that is tapered from theinner diameter toward the outer diameter to form a tip aligned with theouter diameter. The second plunger can be coupled with the bottom end ofthe traveling valve. The second plunger can be configured to reciprocatewithin a pump barrel. The bottom end of the second plunger can beadapted to direct particulate into the second plunger and away from thepump barrel upon each downstroke of the plunger assembly. Upon eachupstroke, the traveling valve is closed and the standing valve is openedto cause a vacuum within the pump barrel to draw fluid into the plungerassembly below the traveling valve. Upon each downstroke, the travelingvalve is opened and the standing valve is closed to force the fluidthrough the traveling valve and up to the surface. In some embodiments,the tapered edge can have two or more different degrees of taper along alength of the tapered edge.

For a fuller understanding of the nature and advantages of the presentinvention, reference should be had to the ensuing detailed descriptiontaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a cross-sectional side view of a downwell pump accordingto embodiments of the invention.

FIG. 2 shows a cross-sectional top view of the downwell pump of FIG. 1positioned within an outer tubing and larger casing string according toembodiments of the invention.

FIG. 3 shows a cross-sectional side view of a stationary plungerassembly according to embodiments of the invention

FIG. 4 depicts the plunger of FIG. 1 according to embodiments of theinvention.

FIG. 4A shows a more detailed view of a tip of the plunger of FIG. 4according to embodiments of the invention.

FIG. 5 shows a tip of a plunger having an arc of constant taperaccording to embodiments of the invention.

FIG. 6 depicts a tip of a plunger having an arc of variable taperaccording to embodiments of the invention.

FIG. 7 shows a cross-sectional view of the plunger assembly of FIG. 1according to embodiments of the invention.

FIG. 8 shows an exploded view of the plunger assembly of FIG. 1according to embodiments of the invention.

FIG. 9 shows the check valves of FIG. 1 in an open position according toembodiments of the invention.

FIG. 9A shows a more detailed view of an open check valve of FIG. 9according to embodiments of the invention.

FIG. 10 shows the check valves of FIG. 1 in a closed position accordingto embodiments of the invention.

FIG. 10A shows a more detailed view of a closed check valve of FIG. 10according to embodiments of the invention.

FIG. 11 shows the pumping system of FIG. 1 during a downstroke accordingto embodiments of the invention.

FIG. 12 shows the pumping system of FIG. 1 during an upstroke accordingto embodiments of the invention.

FIG. 13A is a schematic diagram of a top section of a pumping systemaccording to embodiments of the invention.

FIG. 13B is a schematic diagram of a plunger of the pumping system ofFIG. 13A according to embodiments of the invention.

FIG. 13C is a schematic diagram a middle section of the pumping systemof FIG. 13A according to embodiments of the invention.

FIG. 13D is a schematic diagram of a diluent zone of the pumping systemof FIG. 13A according to embodiments of the invention.

FIG. 13E is a schematic diagram a bottom section of the pumping systemof FIG. 13A according to embodiments of the invention.

FIG. 13F is a schematic diagram of a hollow rod of the pumping system ofFIG. 13A according to embodiments of the invention.

FIG. 13G is a schematic diagram of a plunger assembly of the pumpingsystem of FIG. 13A according to embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In some embodiments, the present invention as illustrated in FIG. 1provides a pump system 100 for pumping fluids to the earth's surface.Pump system 100 includes a pump barrel 102 positioned within an outertubing string 104 or well casing 158 as seen in FIG. 2. Well tubing 104can be contained within a larger casing string 158. Referring back toFIG. 1, pump barrel 102 can be cylindrical in geometry and has a bottomend 106 where a standing valve 108 is disposed. A top end of the pumpbarrel 102 can extend to the ground surface. In some embodiments, pumpbarrel 102 and standing valve 108 remain in a fixed position downwell,while a plunger assembly 112 is reciprocated within the pump barrel 102to draw fluid to the surface. The function and structure of plungerassembly 112 is described in greater detail in the discussion of FIG. 7.Other embodiments, such as shown in FIG. 3, have a fixed plungerassembly 160 and a reciprocating pump barrel 162 and standing valve 164to draw fluids to the surface. Fixed plunger assembly 160 can havesimilar features as plunger assembly 112 described herein. As shown inFIG. 1, pump system 100 can also include a rod 110 that is connected toa plunger assembly 112. Rod 110 and plunger assembly can be configuredto fit within pump barrel 102. In some embodiments, rod 110 can behollow and can form a lumen 134 through which the produced fluids mayflow. The rod 110 can include a top end and a bottom end. The top endcan be coupled to a surface pumping unit as is known in the art. Thebottom end of the rod 110 may be coupled with the plunger assembly 112.The rod 110 is translatable to reciprocate the plunger assembly 112within the pump barrel 102 to produce fluid from the well.

The fluid conduit drive rod 110 provides a smaller cross-section and/ordiameter than conventional pump fluid paths. This smaller cross-sectionincreases the velocity of the pumped fluid. The increased velocityallows any solids in the pumped fluid to be propelled to the surface ofthe well and prevents the solids from settling out of the fluid as itmoves towards the surface. In conventional pumps, the lower fluidvelocity allows the solids to settle out and form large plugs within themain tubing. For example, the inner diameter of rod 110 may be in therange from about 1.0 inch to about 1.5 inches.

In operation, rod 110 is translated downward to slide plunger assembly112 further into pump barrel 102 (referred to as the downstroke). In sodoing, standing valve 108 is forced closed and traveling valve 144 isforced open due to the presence of a fluid within pump barrel 102. Thefluid entering plunger assembly 112 passes upward where it may beevacuated from the pump. In some embodiments, the fluid is evacuatedthrough a main tubing string or pump barrel positioned outside of therod. In other embodiments, the fluid can be evacuated through the lumen134 of rod 110. In such systems, rod 110 serves as a conduit for theproduced fluid to reach the surface. Here, the rod 110 is reciprocatedto drive the plunger assembly 112 while simultaneously having the fluidflow within the rod 110. In such embodiments, the lumen 134 has asmaller cross-section and/or diameter than the pump barrel 102 or maintubing string used in conventional systems. This allows the producedfluid to be drawn to the surface with a higher velocity, propelling anysand or other solids to the surface. This prevents a buildup of solidswithin the pump barrel 102 and plunger assembly 112, reducing the wearassociated with sand getting between the two components and extendingthe life of the pump. Additionally, by including the pumped fluidswithin the hollow rod 110, there is no need to pull a wet pump, as thefluid is transported through the lumen 134 in the center of the pumpsystem and all components are accessible without opening the fluidconduit.

After the downstroke, the rod 110 is then lifted upward (referred to asthe upstroke) to close traveling valve 144 and to open standing valve108. This action causes a vacuum within pump barrel 102, causingstanding valve 108 to lift and production fluids to enter into pumpbarrel 102 and/or conduit 110. On the next downstroke, the process isrepeated to pump additional fluids out of the well. The traveling valves144 and standing valve 108 function in a similar manner to pump fluidsin embodiments where the pump barrel 102 is reciprocated while theplunger assembly 112 remains stationary.

Plunger assembly 112 can include one or more plungers 114 and at leastone traveling valve 144. The structure of each plunger 114 is describedin greater detail in the discussion of FIG. 4. Each of the one or moreplungers 114 can include a top end, a bottom end, and a cylindricalbody. One or more traveling valves 144 may be positioned near the bottomend 106. In embodiments having multiple plungers 114, one or moretraveling valves 144 can be positioned between the plungers 114. Anaperture can be formed in the cylindrical body and can define an innerdiameter of each plunger 114. Each plunger 114 can include a sharpenedleading edge formed from a tapered section of the plunger 114. Thetapered portion can be tapered from the inner diameter toward an outerdiameter of the plunger 114 to form a tip aligned with the outerdiameter. In some embodiments, the top end of a first plunger 114includes a first portion and a second portion that are tapered towardsthe outer diameter of the first plunger 114. The first portion and thesecond portion can have different degrees of taper. For example, thefirst portion can have an angle in the range of 5° to 30°, and in somecases of approximately 15°, while the second portion can have a largerangle than the first portion, such as an angle in the range of 45° to80°, and in some cases of approximately 60°. In other embodiments, thesecond portion can have a smaller angle than the first portion. In someembodiments, the top end may include more than two portions that aretapered. Additionally, top end may have a single portion with a degreeof taper that gradually changes from a tip of the top end to a distalside of the top end.

A connector 140 can be coupled within first plunger 114 spaced adistance below the top end. The connector 140 can then be coupled to abottom end of a drive rod of a conventional system or a hollow rod orother conduit 110 as described above. The connector 140 can beconfigured to include a lumen such that fluids can move upwardly throughthe connector 140 and the conduit 110 upon each upstroke and downstrokeof the plunger assembly. The low coupling position of connector 140within the first plunger 114 eliminates the funneling effect seen inconventional pumps that directs solids towards the interface between theplunger and the pump barrel wall. Rather, the lower coupling positionenables solids to pass through the central aperture of the first plunger114 to greatly reduce the wear between plunger assembly 112 and pumpbarrel 102, thereby prolonging the life of the pump system 100. Byconstructing pump system 100 in this manner, a tighter fit may beprovided between plunger assembly 112 and pump barrel 102 withoutexperiencing gaulding. The tighter fit can be achieved, for example,where an outer diameter of first plunger 114 is between about 0.001inches and about 0.002 inches of a diameter of the inner wall of pumpbarrel 102. Additionally, a higher pump efficiency may be achieved alongwith additional production of fluids due to the tighter fit of thecomponents. Further, by reducing the amount of sand between plungerassembly 112 and pump barrel 102, less well pulling is also required. Assuch, lower operating costs may be achieved resulting in higher profits.

In some embodiments utilizing hollow rods 110, a fluid inverter 150 iscoupled between the connector 140 and hollow rod 110. Fluid inverter 150ensures that the produced fluid is directed from the first plunger 114and/or the pump barrel 102 to inner lumen 134 of the hollow rod 110.Pumping systems 100 having hollow rods 110 and fluid inverter 150 mayalso include a sealing unit 152 that prevents the flow of productionfluids upwardly through the outer tubing casing 104. This ensures thatthe fluid flow may be diverted by fluid inverter 150 into hollow rod110.

The invention provides techniques for preventing or greatly reducing theamount of accumulated sand and other solids at the top of the firstplunger 114 to prevent solids from being deposited between the firstplunger 114 and pump barrel 102. This may be accomplished, for example,by moving connector 140 from the top of the first plunger 114 such thatit is disposed within the first plunger 114 at a distance below the topend of the first plunger 114. For example, connector 140 can be spacedbetween about 1.0 inch and 6.0 inches from the top end of the firstplunger. In this way, coarse particulate will not tend to accumulate atthe top of the first plunger 114. Further, the wall of the first plunger114 may be inwardly double tapered so that the first plunger 114 acts asa scraper on the upstroke to scrape the solids from the walls of thepump barrel 102.

On the downstroke of plunger assembly 112, standing valve 108 closes andtraveling valve 144 opens to permit fluid to pass upwardly throughplunger assembly 112. Upon the upstroke of plunger assembly 112,traveling valve 144 closes and standing valve 108 opens in a mannersimilar to that previously described with pump system 100. Becauseconnector 140 is disposed within first plunger 114, connector 140 doesnot assist in accumulating solids on top of top end of first plunger114. Instead, the open top end serves to direct or funnel sand or othersolids into the interior of first plunger 114 and the plunger assembly112 and away from an inner wall 142 of pump barrel 102. Further, uponthe downstroke of plunger assembly 112, fluid that is moved upwardlythrough the plunger assembly 112 catches the solids and moves themupward without causing any damage to the pump system 100. Moreover, thesharpened edge at top end of first plunger 114 serves to scrape andclean the walls of pump barrel 102 upon each upstroke. In this way, thechances for having sand or other coarse particulate accumulate betweenplunger assembly 112 and pump barrel 102 are eliminated or greatlyreduced.

A second plunger 116 may be included at a bottom end of the plungerassembly 112. The second plunger 116 can include the same designcharacteristics as the first plunger 114 and may be flipped 180 degrees,such that the leading edge and tapered portion are near a bottom end ofthe second plunger 116. The sharpened leading edge of the second plunger116 can scrape against the pump barrel inner wall 142 and the taperedportion can direct any solids into the center aperture of the plungerassembly 112 upon each downstroke of the plunger assembly 112. Thesecond plunger 116 is especially useful in horizontal pumping operationswhere sand and other solids can settle to a bottom, or side wall 142, ofthe pump barrel 102. The sharpened leading edge can then scoop up thesolids and prevent the solids from getting wedged between the plungerassembly 112 and the pump barrel wall 142.

In some embodiments, multiple traveling valves 144 are included. Thestructure of traveling valves 144 are discussed more in the descriptionof FIG. 7. For example, some pumping systems 100 may include multipletraveling valves 144 positioned between the first and the secondplungers 114 and 116. For example, a top end of a first traveling valve144 may be coupled with the bottom end of the first plunger 114. A topend of a second traveling valve 146 may be coupled with a bottom end ofthe first traveling valve 144. Second traveling valve 146 can beconfigured to have the same features as traveling valve 144 as describedherein. A second plunger 116 may be coupled with a bottom end of thesecond traveling valve 146. In some embodiments, the first travelingvalve 144 has a female connector and the second traveling valve 146 hasa male connector that can interface with the female connector. Theseconnectors may be reversed, and in some embodiments, other couplingmechanisms may be used to secure the components of the plunger assembly.These valves can ensure that solids do not fill the plunger assembly 112during a shut down or power failure. Smaller amounts of solids can betrapped at each traveling valve 144, such that less fluid pressure isneeded to force each traveling valve 144 open.

Additionally, some pumping systems 100 may include a traveling valve 148positioned above the plunger assembly 112, near the bottom end of theconduit 110. Traveling valve 148 can have the same features as travelingvalve 144, but is positioned above the plunger assembly 112. Thistraveling valve 148 prevents any solids from produced fluids that havebeen pumped beyond the plunger assembly 112 from settling within theplunger assembly 112. Instead, any solids that settle out of the pumpedfluid would be stopped at the traveling valve 148 atop the plungerassembly 112. The use of multiple traveling valves 144 can also preventgas locking, as the upper traveling valve 148 prevents hydrostatic fluidcolumn pressure above the plunger assembly 112 from holding the lowertraveling valve or valves 144 and 146 closed. Thus, the lower travelingvalves 144 and 146 can open and let in more produced fluid.

Pumping system 100 may include one or more check valves 156 positionedalong the conduit 110. The structure of check valves 156 is described ingreater detail in the discussion of FIGS. 9-10B. Check valves 156 canserve similar functions as upper traveling valve 148, preventing bothgas lock and large deposits of solids from forming on the plungerassembly 112. By including a series of check valves 156 positioned alonga length of the hollow rod 110, the size of deposit of solids on eachcheck valve 156 is reduced, as is the amount of hydrostatic fluid columnpressure. Thus, on startup, the pumping system 100 can move a singlecheck valve section at a time, reducing the force needed to start thepump system 100.

FIG. 4 shows a more detailed view of the first plunger 114 and secondplunger 116 of FIG. 1. While the following description refers to plunger114 for convenience, it will be appreciated that second plunger 116 canhave the same features. Plunger 114 can be used in a the hollow rodpumping system 100 described in FIG. 1 or can be used in otherapplications, such as conventional pumping systems. For example, plunger114 may be utilized as first plunger 114 and/or second plunger 116.Plunger 114 can be configured to fit within a pump barrel of a downwellpump and may have a cylindrical body 118. The cylindrical body 118 mayinclude a top end 136 and a bottom end 138 and may define an aperture120 that can receive any pumped fluids. The aperture 120 can define aninner diameter 122 of the plunger body 118. Plunger 114 can bepositioned on a top end and/or a bottom end of a plunger assembly. Insome embodiments, the plunger 114 can include a tapered portion ortapered leading edge 124. Tapered leading edge 124 may be positioned ateither the top end 136 or the bottom end 138. The placement of theleading edge 124 correlates with whether plunger 114 is at the top endor bottom end of a plunger assembly. The tapered leading edge 124enables any sand or other solid precipitate within a produced fluid tobe forced into the aperture 120 of the plunger 114 instead of resting ontop of the plunger 114 or between the plunger 114 and an inner wall ofthe pump barrel. In some embodiments, it may be desirable for thetapered leading edge 124 to end in a sharp point 126. A sharp point 126ensures a tight fit between the edge of the plunger 114 and the innerwall of the pump barrel. In some embodiments, the sharp point or pointedtip 126 has an outer diameter 128 within about 0.002 inches of an innerdiameter of the pump barrel to ensure a tight fit. The tight fit ensuresthat solids will not get between the pump assembly and the pump barreland also allows for increased pump efficiency. In some embodiments, thetight fit may be further enhanced by incorporating a wear resistantand/or lubricating coating on some or all of the surfaces, such as theinner diameter 122 and/or the outer diameter 128 of the plunger 114. Bycoating the outer surface of the plunger 114, the plunger 114 isprevented from sticking within the pump barrel, while allowing a tightertolerance fit. Galling and other wear can also be reduced using thecoating on the outer diameter 128 of the plunger 114. The coating on theinner surface of the plunger 114 can protect the inner diameter 122 ofthe plunger 114 from being eaten away by any corrosive gases or othermaterials within the produced fluid. The coating can also prevent anyabrasive solids from damaging the plunger body 118.

A tapered leading edge having a rounded or otherwise non-pointed tip mayallow for sand or other precipitate to be wedged between the tip and thepump barrel. A pointed tip 126 can seal against the inner wall of thepump barrel to help eliminate any solids that can get trapped betweenthe outer diameter 128 of the plunger 114 and the inner wall of the pumpbarrel, reducing the amount of wear of the plunger 114, pump components,and pump barrel.

The tapered leading edge 124 is tapered from the inner diameter 122toward the outer diameter 128 of the plunger body 118. The taperedleading edge 124 can form a sharpened tip 126 that is aligned with theouter diameter 128. The sharpness of the tapered leading edge 124 may belimited to prevent excessive or premature wear of the point. When theedge loses sharpness, the seal against the pump barrel is compromised,allowing solids to enter the interface between plunger 114 and the pumpbarrel. A lesser degree of taper can provide a robust solution whilestill keeping sand and other precipitates out from between the pumpbarrel and the plunger 114. A taper that funnels solids into theaperture 120 of plunger 114 while providing a sturdy tip can be achievedby a leading edge 124 including a first section 130 forming the tip 126of the leading edge 124 to seal against the pump barrel and guide solidsinward and a second section 132 that funnels solids into the aperture120. In some embodiments, the first section 130 has a smaller degree oftaper than the second section 132 as seen in FIG. 4A. For example, thefirst section 130 may have a taper of about 15 degrees while the secondsection 132 may have a taper of about 60 degrees. In some embodiments,the second section 132 can be machined, molded, or otherwise forged intothe plunger 114. The first section 130 can then be formed at an end ofthe second section 132 proximal to the leading edge 124. For example,the second section 132 can be ground or otherwise deformed at an angleto form the first section 130 having a lesser degree of taper. Therespective tapers can be of any degree. For example, the amount of taperfor the first section 130 and the second section 132 can range frombetween 5 and 80 degrees. In some embodiments, the first section 130 canhave a taper of between about 5-30 degrees. The second section 132 canhave a taper of between about 45-80 degrees. For example, the firstsection 130 can have a taper of about 15 degrees and the second section132 can have a taper of about 60 degrees. In some embodiments, thesecond section 132 can have a smaller degree of taper than the firstsection 130 in some embodiments.

Embodiments of the invention can taper the leading edge 124 withdifferently shaped tapers. For example, the leading edge 124 can includeadditional sections having different degrees of taper to create adesired taper geometry to accommodate various precipitate types. FIGS. 5and 6 show close up views of tips of plungers having differentgeometries of taper in accordance with some embodiments of theinvention. In FIG. 5, a tapered section 224 can be a single section witha curved taper connecting an inner diameter 222 to an outer diameter228. The tapered section 224 can include a radius of constant curvature,such as a circular arc. Tapered section 224 can terminate in a pointedtip 226 that is aligned with the outer diameter 228. FIG. 6 shows atapered section 324 forming an arc having radius of variable curvaturesuch that parts of the tapered section 324 are more severely taperedfrom an inner diameter 322 towards an outer diameter 328 of the plunger.Tapered section 324 can terminate in a pointed tip 226 that is alignedwith the outer diameter 328. Other shapes for a tapered section caninclude any curved shape or combination of curved shapes and/or linearsections that ends in a pointed tip aligned with the outer diameter ofthe plunger.

Conventional pumps use longer plungers to account for inefficiencies inthe pumping of fluids. The higher efficiency attributed to the tighterfit of plunger 114 allows plunger 114 to be produced having a shorterlength than a conventional plunger while providing comparable, and inmany cases, superior efficiency. For example, the plunger 114 may have alength of between about 6 inches and 24 inches. The shortened length ofplunger 114 enables plunger 114 to be used in horizontal wells, as wellas vertical wells. The shortened length allows the plunger 114 totraverse around a heal or radius of the pump barrel without binding orsticking.

FIGS. 7 and 8 depict cross-sectional and exploded views, respectively,of plunger assembly 112 that has been removed from a pump barrel.Plunger assembly 112 includes plungers 114 and 116 as described abovewith FIG. 4 at both a top and a bottom of the assembly 112,respectively. Plunger assembly 112 can be utilized in pumps such aspumping system 100 in FIG. 1. In some embodiments, a single plunger 114may be used, positioned at the top of the assembly 112. Each plunger 114and 116 can include a tapered leading edge 124. By using a plunger 114and 116 at both a top end and a bottom end of the pump assembly 112,precipitate can be funneled or otherwise directed into a centralaperture 120 of the plunger 114 on both the downstroke and the upstrokeof the pump in a downhole pump operation. In horizontal pumpingoperations, the use of plungers 114 and 116 on both ends of the plungerassembly 112 ensures that any solids are pushed or scooped into a centerof the plunger 114 and/or 116 on both the upstroke and the downstrokemotions.

The plunger assembly 112 can also include two or more traveling valves144. Each traveling valve 144 can have a cylindrical body and include acentral aperture to enable fluid to pass through the body. A sealingelement can be movably seated in the aperture to seal the travelingvalve 144. For example, the aperture can have a circular shape and thesealing element may be a spherical stainless steel ball having adiameter larger than that of the aperture. Any other shape of apertureand sealing element may be used such that the sealing element cancompletely seal the aperture. Sealing elements may be constructed of anymaterial of sufficient density to seal the aperture on each upstroke ofthe plunger assembly 112 and to enable the sealing element to unseatfrom the aperture to allow fluid to pass through the cylindrical bodyupon each downstroke of the plunger assembly 112. Plunger assemblies 112may include multiple traveling valves 144 and 146 positioned between thefirst and the second plungers 114 and 116. Traveling valve 146 can havethe same features as traveling valve 144. For example, a top end of afirst traveling valve 144 may be coupled with the bottom end of thefirst plunger 114. A top end of a second traveling valve 144 may becoupled with a bottom end of the first traveling valve 144. A secondplunger 116 may be coupled with a bottom end of the second travelingvalve 144. In some embodiments, the first traveling valve 144 has afemale connector and the second traveling valve 144 has a male connectorthat can interface with the female connector. These connectors may bereversed, and in some embodiments, other coupling mechanisms may be usedto secure the components of the plunger assembly.

In some embodiments, traveling valves 144 can be coupled with plungers114 and/or 116 using connecting pieces 154. In other embodiments,traveling valves 144 can be coupled directly with plungers 114 and/or116 or by any other component or mechanism. The use of multipletraveling valves 144 ensures that solids do not fill the pump during ashut down or power failure. Smaller amounts of solids can be trapped ateach traveling valve 144, such that less fluid pressure is needed toforce each traveling valve 144 open. A traveling valve 148 can also bepositioned above the plunger assembly 112 near the first plunger 114.This traveling valve 148 can have the same features as traveling valve144 and prevents any solids from fluids that have been pumped beyond theplunger assembly 112 from settling within the plunger assembly 112.Instead, any solids that settle out of the pumped fluid would be stoppedat the traveling valve 148 atop the plunger assembly 112. The use ofmultiple traveling valves 144 can also prevent gas locking, as the uppertraveling valve 144 prevents hydrostatic fluid column pressure above theplunger assembly 112 from holding the lower traveling valve or valves144 and 146 closed. Thus, the lower traveling valve 144 can open and letin more produced fluid.

In some embodiments, the plunger assembly 112 can be implemented withina conventional pumping system. Plunger 114 can be coupled with a driverod that reciprocates to drive the plunger assembly 112 up and down thewell. The pumped fluid in a pump having a conventional drive rod flowsbetween the pump barrel and an outer tubing string. In otherembodiments, the pump assembly 112 is coupled with a hollow drive rodthat serves a fluid conduit. The fluid conduit defines a path for theproduced fluid to be pumped to the surface. The fluid conduit caninclude a hollow cylinder, with the hollow portion acting as the fluidpath and can be aligned with the central aperture 120 of the plunger114. In some embodiments, a connector 140 is included to couple a fluidinverter 150 to plunger 114. Fluid inverter 150 can be included todivert the pumped fluid into the fluid conduit. The fluid conduit can becoupled to the surface pump and can reciprocate to drive the plungerassembly 112 while serving as a conduit for the pumped fluid. By using afluid conduit as described herein, the produced fluids and anyprecipitate solids are contained within an inner tubing string of thepump. Thus, no fluids or solids can get between the pump and the outertubing, so if the pump must be pulled, there will be no fluid spills. Inother words, it eliminates the need to pull a wet well. This can savetremendous amounts of time and money, while providing a much saferpumping operation for both the crew as well as the environment.

In embodiments where the plunger assembly 112 includes a fluid conduitdrive rod, there is no wear between the rod and the tubing as inconventional systems due to the use of a central fluid path.Additionally, the plunger assembly 112 may include a lubricating fluidbetween an outer tubing string (not shown) and a pump barrel 102 tofurther reduce wear of the pump system. Additionally, collars of thefluid conduit may be coated in a wear resistant and/or lubricatingcoating to prevent the collars from wearing on the inside of the outertubing string.

FIGS. 9-10B show a pump system having a plurality of check valves 156along a length of a conduit 110. Each check valve 156 can have acylindrical body and include a central aperture to enable fluid to passthrough the body. A sealing element can be movably seated in theaperture to seal the check valve 156. For example, the aperture can havea circular shape and the sealing element may be a spherical stainlesssteel ball having a diameter larger than that of the aperture. Any othershape of aperture and sealing element may be used such that the sealingelement can completely seal the aperture. Sealing elements may beconstructed of any material of sufficient density to seal the apertureto hold back the hydrostatic pressure above the plunger assembly 112.This allows the traveling valve to open much easier without havingthousands of pounds of pressure keeping it closed. The sealed checkvalves 156 also prevent high volumes of solids from settling down on theplunger assembly should there be a power failure. The check valves 156also help to preventing gas locking. Any gas in the hollow rod iscompressed faster, opening the check valves 156, allowing the gas andfluid through.

Fluid conduit rods 110, such as those described in FIG. 1, can include aseries of check valves 156 positioned at intervals between the plungerassembly and the surface. In some embodiments, the check valves 156 maybe positioned at equal intervals along the entire length of the pumpsystem. By including a series of check valves 156, any solids in theproduced fluid that is not propelled to the surface can be preventedfrom settling out of the fluid and forming a large pile on the pumpsystem. Any solids can settle evenly on each check valve 156, preventinga large plug of solids from forming on a single location, such as theplunger assembly, during a power failure or shut down. Smaller, evenlyspaced plugs, along with fairly even amounts of fluid and gas, areformed at each check valve 156 along the tubing string or fluid conduit110. This even distribution of pumped substances ensures that startingup the pump system is easier when power is restored. A domino effect iscreated, where the pump only lifts a single check valve 156 and smallplug of solids until the gas compresses in that zone. Then as the fluidin that zone hits the next check valve 156 above, the fluid will openthat check valve 156 and start lifting the solids and fluid in the nextzone. Thus, the domino effect lifts one zone after another until thewhole tubing string or hollow rod 110 is back in motion moving upward tothe surface. Along with the check valves 156, a pair of traveling valves(not shown) may be included. Together, the two valve sets help preventsolids from sticking the plunger assembly in the pump barrel as well aspreventing gas lock as described above. As shown in FIGS. 9 and 9A, uponeach downstroke of the pumping system, the check valves 156 open,allowing the fluid to flow up to the surface. Upon each upstroke, orupon shutdown of the pump, the check valves 156 close, as shown in FIGS.10 and 10A.

FIGS. 11-12 show the operation of the pumping system 100 described inFIGS. 1-10A. At a top of pumping system 100 is a check valve 156. Belowcheck valve 156 is a hollow rod 110 which carries fluid and acts as thepower string. Below hollow rod 110 are the fluid inverter 150 andplunger assembly 112. Plunger assembly 112 can include one or moreplungers 114 and traveling valves 146. As the pumping system is started,fluid saturated with solids is lifted and forced into the fluid inverter150 upon each downstroke shown in FIG. 11. In operation, rod 110 istranslated downward to slide plunger assembly 112 further into pumpbarrel 102 on each downstroke. In so doing, a standing valve (not shown)is forced closed and traveling valve 146 is forced open due to thepresence of a fluid within pump barrel 102. The fluid entering plungerassembly 112 passes upward where it may be evacuated from the pump. Uponeach upstroke, the rod 110 is then lifted upward to close travelingvalve 146 and to open the standing valve as shown in FIG. 12. Thisaction causes a vacuum within pump barrel 102, causing standing valve108 to lift and production fluids to enter into pump barrel 102 and/orrod 110. On the next downstroke, the process is repeated to pumpadditional fluids out of the well. The traveling valves 144 and standingvalve 108 function in a similar manner to pump fluids in embodimentswhere the pump barrel 102 is reciprocated while the plunger assembly 112remains stationary. The fluid inverter 150 transfers the solids andfluid from the larger annulus of a pump barrel 102 into the smallerhollow rod 110. Because the inside diameter of the hollow rod is muchsmaller than the inside diameter of the pump barrel 102, the fluidincreases in velocity, allowing a surface pumping unit to pump at aslower rate of speed and maintain the velocity needed to carry thesolids and fluid to the surface easily.

In a regular well, hydrostatic pressure from the fluid column builds upabove check valve 156. Check valve 156 at the top serves to hold backthe hydrostatic pressure above the plunger assembly 112. This allows thetraveling valve 146 to open much easier without having thousands ofpounds of pressure from the fluid column keeping traveling valve 146closed. It will also prevent high volumes of solids from settling downon the plunger assembly 112 should there be a power failure. The checkvalve 156 also prevents gas locking. Gas locking is the condition whendissolved gas released from solution during the upstroke of the plungerassembly 112 appears as free gas between the valves. On the down stroke,pressure inside the pump barrel 102 completely filled up with gas maynever reach the pressure needed to open the traveling valve 144. On theupstroke, the pressure inside the pump barrel 102 never decreases enoughfor a standing valve (not shown) to open and allow liquid to enter theplunger assembly 112. Thus, no fluid enters or leaves the plungerassembly 112 and the pumping system 100 is locked. In pumping system100, the traveling valve 144 opens with each stroke the moment ittouches the fluid. Even lifting as little as half a cup of fluid, thepumping system 100 stays operational. On the upstroke the gas from thelarger annulus of the pump barrel 102 is forced into the smaller hollowrod 110. The gas in the hollow rod is compressed much faster, openingthe check valve 156, allowing the gas and fluid through. The closeproximity of the fluid inverter 150 to the plunger assembly 112 ensuresthat the production of fluid is achieved quickly, even when gas ispresent in the upper portion of the pumping system 100, furthereliminating and/or preventing a gas locked state. In a conventionalpump, gas locking would occur with the presence of this released gasbetween the valves.

FIGS. 13A-13G schematically illustrate cross-sectional view of top,middle, and bottom sections, respectively, of another embodiment of apumping system 1100. FIG. 13A shows a top portion of pumping system1100, including a surface unit 1170. FIG. 13B depicts a plunger 1172shown in FIG. 13A. FIG. 13C shows a middle portion of pumping system1100, while FIG. 13D shows a diluent zone 1192 as in FIG. 13D. FIG. 13Eshows a lower portion of pumping system 1100. FIG. 13F shows a hollowrod 1110 as shown in FIG. 13E, and FIG. 13G shows a pumping assembly1114 as shown in FIG. 13E. In many aspects, the pumping system 1100 ofFIGS. 13A-13G is identical to the pumping system 100 described in FIGS.1-12, but shown in schematic form. One difference is that pumping system1100 includes a surface unit 1170. Pumping system 1100, includes aplunger assembly 1112, and may be reciprocated up and down by a surfacepump (not shown). A velocity string or hollow rod 1110 may extend upwardfrom plunger assembly 1112 and serve as a conduit for pumped fluids toflow toward surface unit 1170. One or more check valves 1156 may bepositioned along hollow rod 1110. A plunger 1172 may be coupled with atop of hollow rod 1110, near surface unit 1170. In some embodiments,plunger 1172 may be of similar construction as plunger 114 describedherein. Plunger 1172 may include a connector 1174 that couples plunger1172 with a polished rod 1176 of the surface unit 1170. Polished rod1176 may be reciprocated by the surface pump to cause the hollow rod1110 and pumping system 1100 to reciprocate within a well. Producedfluid may pass through plunger 1172 and pass around polished rod 1176.In some embodiments, plunger 1172 may direct the produced fluid into aflow line 1182 where it may be collected.

In some embodiments, surface unit 1170 may include a stuffing box 1186that prevents produced fluids from escaping along the polished rod 1176and diverts the produced fluids into the flow line 1182. The surfaceunit 1170 may also include one or more casing valves 1190 that allow thepressure between the casing 1168 and a well tubing 1104 to be regulated.The surface unit 1170 may also include a diluent line 1184. Diluent line1184 may allow diluent or lubrication to be supplied to a space or zone1192 between the well tubing 1104 and a pump barrel 1102. The diluentmay be delivered to the base of the well via the diluent line 1184 andspace 1192 where it may dilute any oil, reducing the viscosity of theoil to make pumping the oil easier. Any diluent or lubrication may passthrough the diluent line and into an annulus formed along the length ofthe well between the well tubing 1104 and pump barrel 1102. This annulusis similar to the annulus shown in FIG. 2 between well tubing 104 andpump barrel 102. By including a diluent line 1184 that is sealed fromthe production line of hollow rod 1110, any production fluids may bedelivered to the surface unit 1170 without contamination from a diluentor lubricant.

As production fluid is pumped upward to surface unit 1170, the fluidpath is shown by arrows 1188. Production fluid may enter pumping system1100 at a standing valve 1108 and pass through a traveling valve 1144, aplunger 1114, and a fluid inverter 1150. Fluid inverter 1150 may directthe fluid flow into hollow rod 1110 toward an upper traveling valve1148, where the fluid passed into velocity string or hollow rod 1110 fordelivery to the surface. The fluid may pass through one or more checkvalves 1156 on the way to the surface before entering the plunger 1172,which diverts the fluid to flow line 1182.

What is claimed is:
 1. A surface unit for a pumping system, the surfaceunit comprising: a conduit that is reciprocatable to pump produced fluidfrom downwell to the surface unit; a flow line in fluid communicationwith the conduit such that the produced fluid may be collected from theconduit; a pump barrel that separates the conduit from a well tubing; afluid inverter coupled with a bottom end of the conduit and configuredto divert fluids into the conduit, the fluid inverter defining an uppercentral lumen extending through a portion of a length of the fluidinverter, the upper central lumen being in fluid communication with aplurality of fluid ports that each extend at a downward angle from theupper central lumen through an outer surface of the fluid inverter, theplurality of fluid ports being configured to direct fluids from betweenthe pump barrel and an outer surface of the fluid inverter into theupper central lumen and the conduit; a first plunger operably coupledwith the conduit, the first plunger configured to direct the producedfluid to the flow line, the first plunger having an inner diameter, anouter diameter, a bottom end, and an open top end with a tapered edgethat is tapered from the inner diameter toward the outer diameter toform a tip aligned with the outer diameter; a connector configured tocouple the fluid inverter with a second plunger such that a portion ofthe fluid inverter is received within the second plunger, the connectorbeing received within a bottom end of the fluid inverter and within thesecond plunger at a position below the top end; a diluent line in fluidcommunication with a space between the pump barrel and the well tubing,wherein the diluent line is sealed from the conduit and the flow linesuch that a diluent or lubricant may be delivered to the space betweenthe pump barrel and the well tubing via the diluent line withoutcontaminating the produced fluid.
 2. The surface unit according to claim1, further comprising: a polished rod coupled with the conduit, whereinthe polished rod is translatable to reciprocate the conduit.
 3. Thesurface unit according to claim 1, wherein: the tapered edge of thefirst plunger comprises a first portion tapered toward the inner wall ofthe pump barrel and a second portion tapered toward the inner wall ofthe pump barrel, wherein the first portion has a different degree oftaper than the second portion.
 4. A pumping system comprising: a conduithaving a top end and a bottom end, wherein the top end is coupleablewith a surface pumping unit; a flow line in fluid communication with theconduit such that the produced fluid may be collected from the conduit;a pump barrel that separates the conduit from a well tubing, the pumpbarrel comprising a standing valve; a diluent line in fluidcommunication with a space between the pump barrel and the well tubing,wherein the diluent line is sealed from the conduit and the flow linesuch that a diluent or lubricant may be delivered to the space betweenthe pump barrel and the well tubing via the diluent line withoutcontaminating the produced fluid; and a plunger assembly coupled to theconduit near the bottom end, the conduit being translatable toreciprocate the plunger assembly within the pump barrel using anupstroke and a downstroke, the plunger assembly comprising: a fluidinverter coupled with a bottom end of the conduit and configured todivert fluids into the conduit, the fluid inverter defining an uppercentral lumen extending through a portion of a length of the fluidinverter, the upper central lumen being in fluid communication with aplurality of fluid ports that each extend at a downward angle from theupper central lumen through an outer surface of the fluid inverter, theplurality of fluid ports being configured to direct fluids from betweenthe pump barrel and an outer surface of the fluid inverter into theupper central lumen and the conduit; a plunger reciprocatably positionedwithin the pump barrel, the plunger having an inner diameter, an outerdiameter, a bottom end, and an open top end with a tapered edge that istapered from the inner diameter toward the outer diameter to form a tipaligned with the outer diameter; a connector configured to couple thefluid inverter with the plunger such that a portion of the fluidinverter is received within the plunger, the connector being receivedwithin a bottom end of the fluid inverter and within the plunger at aposition below the top end, wherein the top end of the plunger isadapted to direct particulate into the plunger and away from the pumpbarrel upon each upstroke; and a traveling valve positioned at a bottomend of the plunger, wherein upon each upstroke, the traveling valve isclosed and the standing valve is opened to cause a vacuum within thepump barrel to draw fluid into the plunger assembly below the travelingvalve, and wherein upon each downstroke, the traveling valve is openedand the standing valve is closed to force the fluid through thetraveling valve and through the conduit to the surface.
 5. The pumpingsystem according to claim 4, wherein: the conduit further comprises aplurality of check valves disposed along a length of the conduit.
 6. Thepumping system according to claim 4, wherein: the plunger comprises afirst plunger; and the pumping system further comprises a second plungercoupled with the top end of the conduit, the second plunger configuredto direct the produced fluid to the flow line.
 7. The pumping systemaccording to claim 4, wherein: the connector comprises a firstconnector; the pumping system comprises a second connector coupled witha bottom end of a polished rod and with a second plunger at a positionbelow an open top end of the second plunger; and the second connector isconfigured to permit the produced fluid to be moved upwardly through thesecond connector toward the flow line.
 8. The pumping system accordingto claim 4, further comprising: a polished rod coupled with the top endof the conduit, wherein the polished rod is translatable to reciprocatethe conduit and the plunger assembly.
 9. The pumping system according toclaim 4, wherein: the plunger comprises a first plunger and the taperededge comprises a first tapered edge; the plunger assembly furtherincludes a second plunger reciprocatably positioned within the pumpbarrel and spaced apart and coupled with the first plunger; the secondplunger comprises an open bottom end with a second tapered edge that istapered towards an inner wall of the pump barrel; and the bottom end ofthe second plunger is adapted to direct particulate into the plunger andaway from the pump barrel upon each downstroke.
 10. The pumping systemaccording to claim 9, wherein: the first tapered edge and the secondtapered edge each comprise a first portion tapered toward the inner wallof the pump barrel and a second portion tapered toward the inner wall ofthe pump barrel; and the first portion has a different degree of taperthan the second portion.
 11. The pumping system according to claim 9,further comprising: at least two traveling valves disposed between thefirst plunger and the second plunger.
 12. A method for pumping fluidsfrom the ground, the method comprising: placing a pumping system intothe ground, wherein the pumping system comprises: a conduit having a topend and a bottom end, wherein the top end is coupleable with a surfacepumping unit; a flow line in fluid communication with the conduit suchthat the produced fluid may be collected from the conduit; a pump barrelthat separates the conduit from a well tubing, the pump barrelcomprising a standing valve; a diluent line in fluid communication witha space between the pump barrel and the well tubing, wherein the diluentline is sealed from the conduit and the flow line such that a diluent orlubricant may be delivered to the space between the pump barrel and thewell tubing via the diluent line without contaminating the producedfluid; and a plunger assembly coupled to the conduit near the bottomend, the conduit being translatable to reciprocate the plunger assemblywithin the pump barrel using an upstroke and a downstroke, the plungerassembly comprising: a fluid inverter coupled with the bottom end of theconduit and configured to divert fluids into the conduit, the fluidinverter defining an upper central lumen extending through a portion ofa length of the fluid inverter, the upper central lumen being in fluidcommunication with a plurality of fluid ports that each extend at adownward angle from the upper central lumen through an outer surface ofthe fluid inverter, the plurality of fluid ports being configured todirect fluids from between the pump barrel and an outer surface of thefluid inverter into the upper central lumen and the conduit; a plungerreciprocatably positioned within the pump barrel, the plunger having aninner diameter, an outer diameter, a bottom end, and an open top endwith a tapered edge that is tapered from the inner diameter toward theouter diameter to form a tip aligned with the outer diameter; aconnector configured to couple the fluid inverter with the plunger suchthat a portion of the fluid inverter is received within the plunger, theconnector being received within a bottom end of the fluid inverter andwithin the plunger at a position below the top end, wherein the top endof the plunger is adapted to direct particulate into the plunger andaway from the pump barrel upon each upstroke; and a traveling valvepositioned at a bottom end of the plunger, wherein upon each upstroke,the traveling valve is closed and the standing valve is opened to causea vacuum within the pump barrel to draw fluid into the plunger assemblybelow the traveling valve, and wherein upon each downstroke, thetraveling valve is opened and the standing valve is closed to force thefluid through the traveling valve and through the conduit to thesurface; reciprocating the conduit and plunger assembly within the pumpbarrel with at least one upstroke and at least one downstroke; closingthe traveling valve and opening the standing valve upon each upstroke tocreate a vacuum within the pump barrel and plunger assembly to drawfluid into the plunger assembly below the traveling valve; opening thetraveling valve and closing the standing valve upon each downstroke toforce the fluid through the traveling valve and through the conduit tothe surface; and directing particulate into the plunger through the opentop end and away from the pump barrel upon each upstroke with thetapered edge.
 13. The method according to claim 12, further comprising:providing a diluent or lubricant to the space between the pump barreland the well tubing via the diluent line.
 14. The method according toclaim 12, wherein: the reciprocation of the conduit and plunger assemblypumps the produced fluid through the standing valve, the travelingvalve, the plunger, and the fluid inverter that directs the producedfluid into the conduit toward an upper traveling valve where theproduced fluid passes through the conduit to the flow line.
 15. Themethod according to claim 12, wherein: the pumping system furthercomprising a polished rod coupled to the top end of the conduit; and thepolished rod is translatable to reciprocate the conduit and the plungerassembly.
 16. The method according to claim 12, wherein: the plungercomprises a first plunger; and the method further comprises:reciprocating a second plunger in the plunger assembly, the secondplunger comprising an open bottom end with a tapered edge, the secondplunger being coupled with the first plunger; and directing particulateinto the second plunger through the open bottom end and away from thepump barrel upon each downstroke with the tapered edge.
 17. The methodaccording to claim 12, wherein: the plunger comprises a first plunger;the pumping system further comprises a second plunger coupled with thetop end of the conduit; and the method further comprises directing theproduced fluid to the flow line using the second plunger.